1. Field of the Invention:
The present invention relates to a process for controlling cockroaches and other crawling insects by the deployment, in insect crawl and harborage areas in residential and commercial buildings, of polymeric controlled release dispensers containing selected toxicants found to have unusually effective knockdown (KD) and kill efficacy for crawling insects based upon fairly short periods of contact between the insect and the dispenser.
2. Description of the Prior Art:
Various species of crawling insects, especially the hard-to-kill cockroach, have been a target for eradication by man for centuries. Lately, pesticides have been developed which have high toxicity for cockroaches, but such pesticides frequently present environmental hazards when used in effective concentrations. The repeated application of low concentrations of available chemical toxicants reduces the danger to the environment but is also less effective and relatively more expensive. Accordingly, attempts have been made to develop methods and products for the controlled release of crawling insect toxicants over extended periods of time in a manner which is relatively less dangerous to man's environment and also is effective to protect the toxicants from premature degradation.
According to the prior art, insect repellent fabrics in the form of tapes or strips have previously been provided which comprise laminated materials at least one layer of which contains an insecticide, alone or in combination with insect baits or attractants. Representative of this prior art are U.S. Pat. No. 2,911,756 -- Geary and U.S. Pat. No. 3,295,246 -- Landsman et al, although the foregoing references are by no means exhaustive of the prior disclosures concerned with toxicant carriers for pest control. In the Geary patent a flexible sheet or strip is provided with a pressure-sensitive adhesive on one side for mounting the strip on a surface. The other side is provided with an insecticidal and insect attracting composition. An intermediate layer may be provided between the insecticidal composition and the substrate layer, such as cellulose fibers, matted, felted or otherwise joined and bonded to the flexible sheet. When the insecticidal insect attracting compositions are applied to the intermediate layer, the composition is said to be absorbed and kept in close contact therewith. Such devices, of which the Geary structure is typical, have been generally objectionable for a number of reasons, including, ( 1) the external availability on the exposed surface of the dispenser of the main concentration of toxicant, (2) the lack of protection of the toxicant from atmospheric conditions which may result in rapid loss of efficiency, (3) the relatively low control over the rate at which the toxicant becomes available to the environment, and (4) the lack of structural protection of the toxicant layer from abrasion or other mechanical attrition.
The structure disclosed in the Landsman et al patent remedies some of the foregoing deficiencies of Geary by providing a protective surface coating on the laminated insect repellent tape. The essential feature of the Landsman et al structure is said to be the provision of an absorbent paper core layer saturated with a residual insecticide. The tape is then coated with a light (thin) resinous solution of vinyl or polyethylene or nylon merely to form a surface without forming a substantial layer on the exterior face of the tape. Such structures, with their fragile outer facings, are subject to rupture with the possible result of rapid loss of the insecticide which is merely absorbed in the absorbent core layer of paper or other porous material and the certain result of external availability of the toxicant. Further, such structures would appear to fail to adequately protect the toxicant from degradation due to atmospheric exposure, and to provide minimal control over rate of release of the toxicant.
The assignee of the present application has also developed a new technology for imparting active properties to the surface of solid, nonporous polymeric substrate materials by a technique which comprises applying to selected solid, non-porous polymeric substrate materials a solid, non-porous layer of a polymeric composition containing selected activating agents capable of migrating from the layer into and throughout the substrate. The migrating agents are incorporated in the layer in an amount sufficient to produce an effective level of activity on the exterior surface of the substrate. The application of the Herculite technology, known in the industry as the HERCON process, to the production of pesticidally active polymeric materials is generally described in U.S. Pat. Nos. 3,705,938, 3,857,934 and 3,864,468. Additionally, the assignee of this application is also the assignee of pending application Ser. No. 535,658 in the names of Henry Von Kohorn and myself which relates to pesticide dispensers also based upon the HERCON technology.
Applicant is also aware of polymeric controlled release dispensers commercially available from the Shell Corporation which have generally been employed to control flying insects. These dispensers comprise a volatile toxicant known as `dichlorvos` or DDVP, which is released into the surrounding atmosphere and which provides a fumigant action in the treated space. Where the space to be treated is unventilated, satisfactory control of crawling insects may be achieved with such fumigant-action dispensers, but in well ventilated rooms this method of control is less effective. Due to the high volatility of DDVP the dispensers tend to lose their efficacy fairly rapidly and the toxicant odors are bothersome to many people.
The present most widely employed approaches for the control of crawling insects involve the use of sprays which are environmentally or aesthetically generally unacceptable for residential use due to persistent toxicity of materials dangerous to man or animals or unpleasant non-toxicity effects, such as unpleasant odors, staining of surfaces, etc. Additionally, where non-persistent toxicants are employed in sprays, the effective life is short, and therefore expensive and inconvenient reapplications are required to achieve even a minimally acceptable level of control.
Accordingly, an object of the present invention is to provide an effective method for controlling cockroaches and other crawling insects which provides prolonged residual effect, minimizes environmental hazards and prevents premature degradation or loss of the toxicant.